Federal Register: December 20, 2004 (Volume 69, Number 243)
DOCID: FR Doc 04-27088
DEPARTMENT OF TRANSPORTATION
U.S. Citizenship and Immigration Services
CFR Citation: 49 CFR Part 571
Docket ID: [Docket No. NHTSA-2003-14483]
RIN ID: RIN 2127-AH79
NOTICE: Part IV
DOCUMENT ACTION: Final rule.
SUBJECT CATEGORY:
Federal Motor Vehicle Safety Standards; Brake Hoses
DATES: This final rule becomes effective December 20, 2006. The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of December 20, 2006.
Optional early compliance is permitted as of February 18, 2005.
Any petitions for reconsideration of today's final rule must be received by NHTSA not later than February 3, 2005.
DOCUMENT SUMMARY:
This rule updates the Federal motor vehicle safety standard on brake hoses to incorporate the substantive specifications of several Society of Automotive Engineers (SAE) Recommended Practices relating to hydraulic brake hoses, vacuum brake hoses, air brake hoses, plastic air brake tubing, and end fittings. The agency initiated this rulemaking in response to a joint petition from several brake hose and tubing manufacturers.
SUMMARY:
Transportation Department, National Highway Traffic Safety Administration,
SUPPLEMENTAL INFORMATION
Table of Contents
I. Background
II. Notice of Proposed Rulemaking
III. Summary of Comments
IV. Agency Decision to Issue a Final Rule
V. Issues Raised by Commenters and NHTSA's Responses
A. Issues Relating to All Types of Brake Hose
1. Use of the term ``burst''
2. Use of the term ``any''
3. Constriction test method
4. Specification of ozone concentration
B. Hydraulic Brake Hoses
1. General hydraulic brake hose comments in response to the NPRM
2. Hydraulic brake hose manufacturer identification requirements
3. Expansion and burst strength (volumetric expansion) test
4. Tensile strength
5. Water absorption and pressure test, tensile strength, and whip resistance
6. Low temperature resistance test
7. Brake fluid compatibility, constriction, and burst strength
8. End fitting corrosion resistance
9. High temperature impulse test
C. Air Brake Hoses
1. Construction and labeling
2. High temperature resistance
3. Low temperature resistance
4. Ozone resistance
5. Adhesion
6. Air pressure (leakage)
7. Tensile strength
8. Minimum bend radius
D. Vacuum Brake Hoses
1. Swell (fuel resistance)
E. Plastic Air Brake Tubing
1. General comments
2. Construction
3. Labeling
4. Dimensions and tolerances
5. One hundred percent leak test
6. Burst test
7. Moisture absorption
8. Ultraviolet resistance
9. Resistance to zinc chloride and methyl alcohol
10. Stiffness
11. Heat aging adhesion
12. Collapse resistance
13. Oil resistance
14. Ozone resistance
F. Plastic Air Brake Tubing Assemblies and End Fittings
1. General comments
2. Tensile strength
3. Hot tensile strength
4. Vibration leak test
5. Proof and burst test (end fitting retention)
6. Serviceability test
7. End fitting dimensional requirements
8. End fitting corrosion resistance
G. New Types of Brake Hose
H. Metallic Tubing and Pipe
VI. Statutory Bases for the Final Rule
VII. Effective Date
VIII. Rulemaking Analyses and Notices
A. Executive Order 12866 and DOT Regulatory Policies and Procedures
B. Regulatory Flexibility Act
C. National Environmental Policy Act
D. Executive Order 13132 (Federalism)
E. Civil Justice Reform
F. Paperwork Reduction Act
G. National Technology Transfer and Advancement Act
H. Unfunded Mandates Reform Act
I. Plain Language
J. Regulation Identifier Number
Final Rule Regulatory Text
I. Background
On October 30, 1998, three brake hose manufacturers, Elf Atochem
North America, Inc., Mark IV Industrial/Dayco Eastman, and Parker
Hannifin Corporation,\1\ filed a joint petition for rulemaking with
NHTSA. The petitioners requested that certain requirements relating to
brake hoses, brake hose tubing, and brake hose end fittings that are
presently administered by the Federal Motor Carrier Safety
Administration (FMCSA) be incorporated into the brake hose standard
that is administered by NHTSA. The Federal Motor Carrier Safety
Regulations (FMCSR) requirements for brake hoses at 49 CFR 393.45
(Brake tubing and hose, adequacy) and 49 CFR 393.46 (Brake tubing and
hose connections) reference several Society of Automotive Engineers
(SAE) standards that describe the dimensions and performance
requirements for brake hoses and end fittings for hydraulic, vacuum,
and air brake hoses, and also metal and plastic tubing and end fittings
used in brake systems. Specifically, the petitioners requested that the
SAE standards referenced in the FMCSRs be incorporated into 49 CFR
571.106 (Brake hoses) of the Federal Motor Vehicle Safety Standards (FMVSS) that are administered by NHTSA.
\1\ Since the petition was filed, mark IV Industrial/Dayco
Eastman has been acqired by Parker Hannifin Corporation. Elf Atochem
North American, Inc. was integrted into Atofina Chemical, Inc. The
successor petitioning companies are referred to as Parker/Atofina.
The petitioners requested that the application of these SAE specifications be limited to hose, tubing, and fittings used on trucks, trucktrailer combinations, and buses with either a GVWR greater than 10,000 pounds or which are designed to transport 16 or more people, including the driver. In addition, the petitioners requested that the current versions of the SAE specifications be adopted instead of the older versions cited in the FMCSRs.
The joint petition was submitted in light of a 1997 proposal by the
Federal Highway Administration (FHWA), which then administered the
FMCSRs, to delete these provisions. The FHWA stated that because it has
no statutory authority to regulate vehicle manufacturers or
manufacturers of brake hose, tubing, or fittings, all such regulations
should be included in NHTSA's FMVSS rather than in the FMCSRs. The FHWA
proposed adopting a requirement that commercial motor vehicles be maintained in compliance
[[Page 76299]]
with FMVSS No. 106. However, many of the provisions included in the
FMCSRs in this subject area were not included in FMVSS No. 106.
In a 1998 public meeting on the subject, representatives from NHTSA and FHWA said that they favored consolidating all requirements for brake hose, brake tubing, and fittings in FMVSS No. 106, instead of maintaining separate requirements under the jurisdiction of two different agencies. They explained that consolidation of the requirements would, among other things, make them more enforceable. Some of the brake component manufacturers stated their opposition to deleting the SAE specifications for their products. FHWA and NHTSA indicated that anyone opposed to FHWA's proposal was welcome to file a petition for rulemaking requesting that the SAE specifications proposed for deletion from the FMCSRs be incorporated into FMVSS No. 106.
For details about FMCSR's brake hose requirements and additional background behind the joint petitions, please see NHTSA's notice of proposed rulemaking (NPRM) of May 15, 2003 (68 FR 26384, at pages 26384 to 26385).
II. Notice of Proposed Rulemaking
In an NPRM published on May 15, 2003 (68 FR 26384) [DOT Docket No. 0314483] NHTSA announced that it had granted the joint petition for rulemaking to amend FMVSS No. 106. The agency agreed with the petitioners that there was a safety need to transfer the brake hose, tubing, and fitting requirements in Sections 393.45 and 393.46 of the FMCSRs to FMVSS No. 106, before those requirements were removed. NHTSA tentatively concluded that to ensure the continued safety of commercial motor vehicle braking systems, the substantive specifications of the SAE Recommended Practices should be incorporated into FMVSS No. 106, with a few exceptions. This would involve, among other changes, establishing a new category in FMVSS No. 106 for plastic air brake tubing, end fittings, and tubing assemblies.
NHTSA's decision to grant the petition was also based on the fact that FMVSS No. 106 had not been substantially updated in many years. The agency noted that most of the substantive requirements currently in FMVSS No. 106 were originally based on SAE standards and American Society for Testing and Materials (ASTM) standards referenced therein. While the SAE and ASTM standards have been modified over time to keep pace with technological developments in the industry, the substantive requirements of FMVSS No. 106 have remained relatively unchanged. Therefore, NHTSA's proposed changes to FMVSS No. 106 took into account the substantial technological developments that have occurred and sought to align the standard's requirements with standard industry practices. Incorporating many of the SAE standards' performance requirements is consistent with Office of Management and Budget (OMB) Circular A119, which directs federal agencies to use and/or develop voluntary consensus industry standards, in accordance with Pub. L. 104 113, the ``National Technology Transfer and Advancement Act of 1995.''
The agency's proposal differed as follows from the petition:
First, instead of simply incorporating complete SAE standards by reference as the FMCSRs currently do, NHTSA proposed to incorporate only the specific requirements/specifications of the SAE standards that are either more rigorous than those in FMVSS No. 106 or are not present at all in FMVSS No. 106.
Second, the agency did not propose to limit the application of those SAE requirements/specifications to brake hose, tubing, and fittings used on commercial motor vehicles. NHTSA tentatively concluded that all brake hose, tubing, and fittings can and should meet the SAE requirements/specifications, regardless of their end use.
Third, although NHTSA agreed with the petitioners that proposed changes to FMVSS No. 106 should be based on the most recent versions of the SAE standards instead of the older versions cited in the FMCSRs, the agency noted that a number of SAE's standards had been updated since the joint petition was filed. Accordingly, NHTSA proposed to rely on the most recent versions of the SAE standards.
Fourth, the agency did not propose to incorporate SAE standards relating to copper tubing, galvanized steel pipe, or end fittings used with metallic or nonmetallic tubing. These materials are occasionally used in chassis plumbing and since these products are not considered to be brake hoses, NHTSA stated its belief that they are inappropriate for inclusion in FMVSS No. 106.
Fifth, NHTSA did not propose to incorporate the material and construction specifications for Type A and Type B tubing contained in SAE J844, Nonmetallic Air Brake System Tubing, and SAE J1394, Metric Nonmetallic Air Brake System Tubing because the agency tentatively concluded that incorporating those material specifications would be designrestrictive.
Sixth, NHTSA did not propose to incorporate the manufacturer identification requirements in SAE J1401, Hydraulic Brake Hose Assemblies for Use with NonpetroleumBase Hydraulic Fluids, because it tentatively concluded that the manufacturer identification requirements already present in FMVSS No. 106 are sufficient.
III. Summary of Comments
In response to the May 15, 2003 NPRM, NHTSA received comments from the following eleven organizations and companies: SAE International (SAE) and ASTM International (ASTM), which are automotive and industrial standards organizations; Intertek Testing Services (Intertek), a company that tests brake hoses and other products; and the following manufacturers of brake hose products; Goodyear Engineered Products (Goodyear), Dana Coupled Products (Dana), SaintGobain Performance Plastics (SGPPL), Degussa High Performance Polymers (HPP), Parker Hanifin Corporation and Atofina Chemical, Inc. (Parker/Atofina), SMC Corporation of America (SMC), and DuPont Engineered Polymers (DuPont).
Parker/Atofina submitted joint comments to the NPRM and are the successor companies to the parties to the joint petition for rulemaking submitted to NHTSA in 1998. Intertek Testing Services conducts laboratory testing of various products, including brake hoses, and also contracts with NHTSA to perform compliance testing of brake hoses. DuPont submitted comments on June 16, 2004, after the NPRM's comment closing date of July 14, 2003. However, NHTSA has fully considered DuPont's comments.
The commenters generally supported NHTSA's proposal to amend FMVSS No. 106 to include the latest requirements in the SAE brake hose standards for hydraulic, vacuum, and air brake hose and tubing. The commenters raised numerous technical issues, however. For many of proposed tests, commenters provided detailed information on test methods and procedures. The comments also generally supported NHTSA's proposal to specify requirements for plastic brake tubing, and plastic air brake tubing assemblies and end fittings.
IV. Agency Decision To Issue a Final Rule
In this document, NHTSA announces that it has decided to issue a final rule. We have made this decision after we
[[Page 76300]]
have thoroughly reviewed the public comments. We have made a number of
changes in response to the comments. In the few instances where we did
not adopt a comment, we explain why, in light of the need for safety.
We believe that the updated brake hose standard, which combines the most rigorous requirements of the latest SAE standards, and of FMVSS No. 106, meets the need for safety. Significant changes have been made to existing brake hose standards, with the effect of upgrading the performance requirements and test procedures relating to: (a) Hydraulic brake hose; (b) air brake hose; and (c) vacuum brake hose. In addition, we are establishing requirements more specifically tailored for plastic air brake tubing, plastic air brake tubing assemblies and end fittings. NHTSA seeks to ensure safe plastic air brake tubing, and plastic air brake tubing assemblies and end fittings.
In the following sections, we discuss the public comments to the
NPRM, our response to the comments, and how (if this is the case) the
proposed language in the NPRM has been amended in response to the comments.
V. Issues Raised by Commenters and NHTSA's Responses
A. Issues Relating to All Types of Brake Hose
1. Use of the Term ``Burst''
Intertek stated that several proposed requirements in the NPRM referred to the word ``burst'' and noted that ``burst'' was not defined in the proposed regulatory text. Intertek cited SAE J1401, stating that leaks or burst is ``loss of test fluid from the brake hose assembly other than by designated inlet(s) and outlet(s).'' NHTSA notes that in S4 of FMVSS No. 106, ``rupture'' is defined as any failure that results in separation of a brake hose from its end fitting or in leakage. In this final rule, NHTSA retains ``burst'' as a term that is presently used in FMVSS No. 106 to describe a required test or test pressures (as in, for example, a table of burst pressures). Whenever the performance requirement of a brake hose is specified, the word ``rupture'' has been substituted. This is consistent with existing FMVSS No. 106 text and avoids the need to add a definition of ``burst'' to S4.
2. Use of the Term ``Any''
SMC Corporation commented that S11.3 Test requirements (for plastic air brake tubing, plastic air brake tubing assemblies, and plastic air brake tubing end fittings) stating ``* * * capable of meeting any of the requirements'' should be changed to ``all of the requirements.'' [Emphasis added.] NHTSA is not making this recommended change. The term ``any'' has a very specific meaning in the Federal motor vehicle safety standards, including FMVSS No. 106. 49 CFR Part 571.4 specifies that ``(t)he word any, used in connection with a range of values or set of items in the requirements, conditions, and procedures of the standards or regulations in this chapter, means generally the totality of the items or values, any of which may be selected by the Administration for testing. * * * Thus, use of the term ``any'' has the effect of including all of the requirements.
3. Constriction Test Method
The constriction test is conducted to ensure the opening in the brake hose is large enough for the medium (i.e., brake fluid or air) to flow through unimpeded. In the NPRM, NHTSA noted that while the existing FMVSS No. 106 includes constriction requirements, i.e., requirements for minimum passthrough diameter, it does not specify a test procedure. The agency noted that two different constriction test procedures are available: A dropball test and a plug gauge test. The agency proposed to use a plug gauge method, similar to that in SAE J1401, that consists of a spherical end (sized at 64 percent of the brake hose nominal inside diameter for hydraulic brake hose and 66 percent of nominal inside diameter for air brake hose) with a shank and handle that can be inserted into the brake hose end fitting. The weight of the gauge is specified as two ounces, and this weight assists the passage of the spherical end through the fitting. The agency stated that it welcomed comments both on its proposal to specify a plug gauge test instead of a dropball test and on the differences between the plug gauge test specified in SAE J1401 and the one the agency proposed.
Goodyear commented on the proposed constriction test method for air brake hoses, and Dana similarly commented on the constriction testing for hydraulic brake hoses.
Goodyear stated that air brake hose manufacturing may result in curvature in the hose that could impede the gauge from fully entering the brake hose. The agency notes that the proposed regulatory text at S6.12 provided that the brake hose is held in a straight position to overcome such a problem. Holding the brake hose in a straight position allows the gauge to fully enter the brake hose. Goodyear stated that the general practice is to use the rolling ball test (also described in the NPRM, but not proposed as a test method), and recommended that the constriction test method be left to the discretion of the hose/assembly manufacturer. NHTSA notes that the rolling ball test is similar but not identical to the drop ball test. The drop ball test relies on the force of gravity for the ball to drop vertically through the hose; the rolling ball test relies on a sidetoside motion by the tester to go through the hose.
Dana agreed with the plug gauge test but recommended including the option of a drop ball test or an extended plug gauge for hose assembly end fittings that by design do not offer a passage through which a plug gauge can be readily inserted. Dana stated that either the extended plug gauge or the rolling ball would permit constriction inspection without cutting the hose.
In response to the comments about the drop ball test vs. the extended plug gauge test, NHTSA begins by noting that S5.3 Test requirements in both the existing FMVSS No. 106 and proposed regulatory text for FMVSS No. 106 indicate that a hydraulic brake hose is only subjected to one of the test conditions in S5.3.2 through S5.3.11 (existing text) or through S5.3.13 (proposed text) after having met the constriction test requirement in S5.3.1. There is a similar provision for air brake hoses in S7.3 Test requirements. Thus, each brake hose tested to any of the conditions in FMVSS No. 106 would first be inspected for constriction test compliance. If the end fittings or other features of the brake hose do not permit the plug gauge to be used, or would require cutting of the brake hose or end fitting to do so, then constriction testing cannot be conducted prior to one of the other performance tests. Therefore, NHTSA is including the drop ball test in the final rule to provide NHTSA and the manufacturers an alternative to the plug gauge test. In addition, the use of an extended length plug gauge is also included for similar reasons. This will provide some flexibility in the constriction test method for the variety of end fittings likely to be encountered in compliance testing. None of these provisions would preclude a brake manufacturer or assembler from using other means to perform constriction testing, since the purpose of the constriction test is to verify the final inside diameter of a brake hose assembly in a passfail manner.
4. Specification of Ozone Concentration
Many commenters noted an incorrect specification of ozone concentration in the preamble to the NPRM, where the
[[Page 76301]]
units ``parts per million'' were stated, rather than the correct
``parts per hundred million.'' The agency agrees that this was an
oversight, and notes that a change to the regulatory text is not needed, as the proposed text specified the correct units.
B. Hydraulic Brake Hoses
1. General Hydraulic Brake Hose Comments in Response to the NPRM
In general, the commenters agreed with the agency's proposal to
upgrade the hydraulic brake hose requirements in FMVSS No. 106 to those
requirements in SAE J1401. In the NPRM, the agency proposed to keep all
hydraulic brake hose requirements in one section, rather than creating
separate categories of brake hoses for commercial vehicles and non
commercial vehicles. Dana stated that it agrees with this position, and
does not see this as burdensome to the industry as a whole, as most
brake hose manufacturers and light vehicle original equipment manufacturers (OEM) requirements currently exceed the SAE
specifications. Goodyear stated that it currently brands, tests, and
certifies its brake hoses to both FMVSS No. 106 and SAE requirements.
Parker/Atofina was the only commenter to oppose the upgrade in performance standards for all hydraulic brake hoses, stating that hydraulic brake hoses used on recreational boat trailers, motorcycles, allterrain vehicles (ATVs), snowmobiles, and offroad tractors/ trailers and farm implements do not require the same level of severe service performance requirements. NHTSA notes that of the vehicle types listed by Parker/Atofina, the upgraded requirements would only apply to ``motor vehicles,'' (i.e., boat trailers and onroad motorcycles). The other vehicle types are not ``motor vehicles'' regulated by NHTSA. Parker/Atofina also asserted that the FMVSS No. 106 upgrade for all hydraulic brake hoses is unnecessarily cost prohibitive, but provided no cost data for the agency to evaluate.
NHTSA is not adopting Parker/Atofina's recommendation because NHTSA
does not wish to create separate categories of hydraulic brake hose
(e.g., ``commercial'' and ``noncommercial.'') To avoid brake system
failures caused by brake hose ruptures, we believe there is a safety
need for all motor vehicle brake hose to meet rigorous performance requirements.
2. Hydraulic Brake Hose Manufacturer Identification Requirements
Parker/Atofina requested that the agency incorporate into FMVSS No. 106 the full manufacturer identification requirements as provided in SAE J1401. Parker/Atofina states that the agency may not realize that hydraulic brake hoses as defined in SAE J1401 more clearly describe the performance, markings, and requirements for hydraulic brake hose compared with those currently existing in FMVSS No. 106.
In response, NHTSA notes that the requirements for hose manufacturer identification in SAE J1401 are that the hose shall be either embossed or imprinted (threedimensional) on the brake hose cover with the manufacturer's name, or employ the market yarn color scheme (Appendix A) as registered with the Rubber Manufacturers Association. In addition, the marker yarn color scheme or name trademark on the brake hose cover shall be registered with the SAE. SAE J1401 does not include any provision for a brake hose assembler to add identifying markings to the end fittings or by means of a band placed around the brake hose assembly; only requirements for the manufacturer of the brake hose material are specified.
NHTSA further notes that the FMVSS No. 106 requirements for
hydraulic brake hose manufacturer or assembler identification are
specified in S5.2 Labeling. The brake hose manufacturer's designation
(symbol, text, etc.) is registered with NHTSA and labeled on the
outside of the hose. The brake hose assembler's designation is included
on a band placed around the brake hose assembly, or may be stamped into
an end fitting. Labeling exceptions are provided for brake hose
assemblies included as part of a newlymanufactured vehicle. For these
reasons, NHTSA determines that the current labeling requirements fully
meet the agency's needs for identifying the manufacturers of brake hose
or brake hose assemblers. Therefore, in this final rule, NHTSA will not
require any additional labeling or manufacturer identification requirements for hydraulic brake hoses.
3. Expansion and Burst Strength (Volumetric Expansion) Test
NPRMThe expansion test is conducted at test pressures of 1,000 psi and 1,500 psi and is followed by a burst strength test. NHTSA proposed to add language to S5.3.2 specifying that after the hydraulic brake hose assembly withstands water pressure of 4,000 psi for two minutes without rupture, it must ``not rupture at less than 7,000 psi for 1/8 inch, 3 mm, or smaller diameter hose, or at less than 5,000 psi for a hose with a diameter larger than 1/8 inch or 3mm (S6.).''
Public Comments and NHTSA ResponseGoodyear indicated that in addition to the expansion test pressures of 1,000 psi and 1,500 psi, SAE J1401 includes a third test at a higher pressure of 2,900 psi, and recommended that it be added to FMVSS No. 106.
In considering this issue, we note that it was an oversight not to include the third pressure in the NPRM. We did, however, explain that we were generally proposing to incorporate those SAE J1401 requirements that are more rigorous than FMVSS No. 106. We therefore believe it is reasonable to add this pressure for the final rule. We are therefore adding the third test at 2,900 psi to S5.3.2 and to Table 1.
We note, however, that SAE J1401 does not include any expansion requirements for the larger, \1/4\ inch and 6 mm brake hose sizes that are included in FMVSS No. 106. Further, the agency is not able to extrapolate the existing values in FMVSS No. 106, Table 1, Maximum Expansion of Free Length Brake Hose, to determine what expansion limits would be appropriate for the larger brake hose sizes tested at the 2,900 psi expansion test. We are therefore not including at this time expansion requirements for the larger brake hose sizes tested at the 2,900 psi expansion test.
Intertek stated that for the final burst strength requirement in the expansion and burst strength tests, the proposed regulatory text included a 7,000 psi burst strength for \1/8\ inch, 3 mm or smaller diameter brake hoses, and a 5,000 psi burst strength for \3/16\ inch, 4 mm, or larger diameter brake hoses. Intertek noted that this does not include a defined specification for those brake hoses with diameters falling between \1/8\ inch and \3/16\ inch, or between 3 mm and 4 mm. To clarify this issue, in the final rule, the agency has changed the regulatory text to state that brake hoses with diameters greater than \1/8\ inch or 3 mm shall not rupture at less than 5,000 psi. 4. Tensile Strength
NPRMNHTSA proposed that the SAE J1401 fastpull test and 370 pound strength requirement be incorporated into FMVSS No. 106. The agency also proposed to update the ASTM reference for tension testing machines to the latest version of the standard practice.
The agency notes that in the NPRM, the water absorption and tensile
strength requirements were labeled as S5.3.5. However, S5.3.5 as
currently specified in FMVSS No. 106 are the water absorption and burst strength
[[Page 76302]]
requirement test. In this final rule, NHTSA corrects the error. The
water absorption and tensile strength requirements are at S5.3.6.
Public Comment and NHTSA's ResponseAt S6.4 of FMVSS No. 106, the
tensile strength test procedures are specified. ASTM commented that the
latest version of ASTM standard E 4 Standard Practices for Force
Verification of Testing Machines was E 402. In preparing this final
rule, NHTSA determined that E 4 has been revised to E 403. NHTSA is
therefore incorporating by reference ASTM standard E 403 into FMVSS No. 106 at S6.4.
5. Water Absorption and Pressure Test, Tensile Strength, and Whip Resistance
NPRMNHTSA did not propose any changes to the existing water absorption requirements of FMVSS No. 106 but did propose to incorporate SAE J1401's fastpull test and 370pound strength requirement into Standard No. 106's tensile strength test procedure. Accordingly, after being conditioned in water for 70 hours, hydraulic brake hose assembly would be required to meet these heightened tensile strength requirements.
The agency stated that the immersion of the brake hose in water for 70 hours as specified in S6.5 of FMVSS No. 106 is the same as that specified in SAE J1401. However, while the time specification of 70 hours is the same, the preparation of the brake hose specimen and the water soak method are different between the two standards. The preparation in FMVSS No. 106 specifies removal of 1 \1/8\ inches of outer brake hose cover (if present) at the center of the brake hose, without damage to any reinforcing material. Brake hoses tested to SAE J1401 do not have any cutting of the hose. Another difference between SAE J1401 and FMVSS No. 106 is that FMVSS No. 106 specifies soaking the brake hose in distilled water at room temperature (75 degrees Fahrenheit) while J1401 specifies an elevated water temperature of 185 degrees Fahrenheit.
Public Comments and NHTSA ResponseIntertek commented that water temperature is not a great factor regarding the degradation of brake hoses, but that removal of the outer cover may influence the test results because of the possibility of damage to the reinforcing braid when the cover is cut. Goodyear stated that the SAE J1401 procedure was developed to eliminate the potential of yarn damage that may occur when the outer cover of the brake hose is removed by cutting. Goodyear recommended that the water soak procedure in SAE J1401 be used in FMVSS No. 106. Dana noted the discrepancies in the two standards, and stated that it prefers the SAE procedure because it is easier for the technician to perform and has less risk of inadvertent damage to the brake hose. Further, Dana stated its belief that the results of the SAE J1401 and FMVSS No. 106 test methods are similar although the comparison data is about a decade old.
NHTSA agrees with the commenters that by using the SAE J1401 water soak procedure, the likelihood of unintended damage to the brake hose during the process of removing the cover will be eliminated. Thus, in the final regulatory text, NHTSA adopts the water soak procedure in SAE J1401.
6. Low Temperature Resistance Test
NPRMNHTSA did not propose any changes in Standard No. 106's low temperature resistance requirements/procedures.
Public Comments and NHTSA's ResponseDana and Goodyear stated that while FMVSS No. 106 specifies a temperature of minus 40 degrees Celsius, SAE J1401 specifies a lower temperature range of minus 45 degrees Celsius to minus 48 degrees Celsius. Both Dana and Goodyear recommended the use of the lower test temperature as better reflecting the capabilities of the materials used in current day brake hoses.
In the final rule, NHTSA adopts the lower temperature specification recommended by Dana and Goodyear and as provided in SAE J1401. 7. Brake Fluid Compatibility, Constriction, and Burst Strength
NPRMIn the NPRM, NHTSA proposed to use the latest SAE reference RM brake fluid for the brake fluid compatibility test. Because the RM 6605 fluid has superseded the RM6603 fluid, NHTSA did not propose any change in the type of fluid specified for conditioning the hose. NHTSA proposed, however, to increase the conditioning temperature in FMVSS No. 106 to 248 degrees Fahrenheit.
Public Comments and NHTSA's ResponsesGoodyear indicated in its comments that the NPRM language regarding compatibility fluid was incorrect with respect to the version of the SAE compatibility fluid referenced in the existing FMVSS No. 106 and SAE J1401. NHTSA notes that SAE RM6604 is currently referenced in FMVSS No. 106, and SAE RM 6605 is referenced in SAE J1401 (June 2003). The agency correctly identified the compatibility fluid in the proposed regulatory text as SAE RM6605 and therefore will make no change in the final rule.
Goodyear recommended that FMVSS No. 106 reference the latest or current SAE fluid and not cite the specific version (e.g., 04 or 05). NHTSA will not adopt this recommendation. NHTSA will maintain the current system of referencing a specific version of the compatibility fluid, and perform periodic rulemaking as new versions of the test fluid are developed. In this way, the public will have an opportunity to comment on new versions of the compatibility fluid before it is incorporated by reference into FMVSS No. 106.
8. End Fitting Corrosion Resistance
NPRMInstead of referencing either ASTM B11764 or ASTM B 117
Appendix B, both of which are outdated, NHTSA proposed to change the reference in FMVSS No. 106 to the most recent set of ASTM
specifications for salt spray chambers, which are found in ASTM B117
97. NHTSA did not propose any other changes to the end fitting
corrosion resistance requirements/procedures in FMVSS No. 106.
Public Comment and NHTSA ResponseASTM commented that the latest revision of ASTM standard B 117 Standard Practice for Operating Salt Spray (Fog) Apparatus is B 11702. In preparing this final rule, the agency determined that B 117 has been revised to B 11703, and is incorporating B 11703 in FMVSS No. 106 at a new S6.11, End fitting corrosion test. There are no substantive differences between B 11702 and B 11703.
9. High Temperature Impulse Test
NPRMNHTSA proposed incorporating the high temperature impulse test from SAE J1401 into FMVSS No. 106.
Public Comment and NHTSA ResponseGoodyear noted that in the
NPRM's preamble, the text incorrectly stated that the impulse test is
conducted in an air chamber at 259 degrees Fahrenheit, while the
correct specification is 295 degrees Fahrenheit. No change is needed to
the final rule regulatory text, as the correct temperature was specified in the NPRM's draft regulatory text.
C. Air Brake Hoses
1. Construction and Labeling
NPRMNHTSA proposed that plastic air brake tubing be regulated in
its own section in FMVSS No. 106 since it differs significantly in construction and material properties from elastomeric
[[Page 76303]]
rubber hoses. Therefore, NHTSA proposed that any references to
synthetic or natural elastomeric rubber be deleted from S7
RequirementsAir brake hose, brake hose assemblies, and brake hose end
fittings of FMVSS No. 106 since it will no longer be necessary to
differentiate rubber hoses from plastic tubing in S7 and S8. The
proposed text in the NPRM also removed references to ``outside diameter
(OD)'' from S7 and S8 of FMVSS No. 106 since OD measurements are
generally only applicable to tubing, which NHTSA proposed to address in the new section for plastic tubing.
NHTSA also proposed to specify in S7.2.1(e) of FMVSS No. 106 the labeling scheme that is to be used for air brake hose that meets the dimensional requirements of more than one type of end fitting (A, AI, or AII). The proper labeling of such hose has been addressed in several of the agency's legal interpretation letters, and including this language in FMVSS No. 106 would serve to minimize confusion on this issue. The proposed text also stated that a hose intended for use with more than one type of end fitting may be labeled as such, but is not required to be so labeled. This provides flexibility for hose manufacturers to determine how they intend their hoses to be used, and would not require them to label hoses for multiple end fitting designations unless they so desire.
Public Comments and NHTSA's ResponseThe SAE and Parker/Atofina stated that it is necessary to keep the references to synthetic or natural rubber in order to clearly indicate that the fittings intended for use with rubber air brake hose are not to be used with any type of plastic hose (which is similar to plastic tubing but is sized by inside diameter rather than outside diameter). Based upon the comments received, the agency determines that retaining the references to rubber provides beneficial information regarding the use of these brake hoses, and is retaining the existing FMVSS No. 106 language in the final rule.
Comments from the SAE and Parker/Atofina describe the differences in the three types of air brake hose designated as Type A, Type AI, and Type AII. The SAE suggested notes for Table III describing the application of reusable and permanent crimped fittings to each type of hose. The SAE also recommended that the dimensional requirements for Type A hose for use with both reusable and permanent fittings be included in Table III. Parker/Atofina also recommended that the correct dimensions for Type A, AI, and AII hose be included in FMVSS No. 106, and that FMVSS No. 106 should conform to the specifications in SAE J1402 for these dimensions.
Historically, NHTSA has declined to specify dimensions of end fittings, as there are too many different end fitting thicknesses and too many different types. NHTSA notes that the industry has standardized brake hose end fittings. Therefore, on the issue of dimensional requirements for air brake hose intended for use with permanently attached fittings, NHTSA has stated its belief in the May 15, 2003 NPRM and in other rulemaking documents that it was not necessary to include those dimensional requirements in FMVSS No. 106. In the May 15, 2003 NPRM, NHTSA also stated that it believes that many of the brake hose assemblers are truck repair facilities that may be assembling brake hoses with permanently attached end fittings. It follows that these truck repair facilities must pay attention to the type of air brake hose being assembled, to ensure that the hose and end fitting are compatible. In the NPRM, NHTSA stated that it believes that air brake hose conforming to SAE J1402 is presently in use because of FMCSR requirements at 49 CFR 393.45.
Regarding metric sizes of air brake hose, in the NPRM, NHTSA noted that dimensions for metric air brake hoses are not included in FMVSS No. 106, and solicited comments on the dimensions for metric air brake hose (for use with permanently attached, or reusable end fittings) that may be appropriate to include in FMVSS No. 106. Since it received no comments on this subject, NHTSA will not include metric air brake hoses in Table III.
In the final rule, the agency is adopting the dimensional requirements for Type A air brake hose in Table III, as recommended by the SAE and Parker/Atofina, and is including the suggested notes for Table III. Table III's title, and its reference in S7.1, Construction, are changed to no longer reference ``reusable'' end fittings because, as the SAE indicates, the air brake hose in the table may be used with either reusable or permanent fittings. The agency concludes that it is also appropriate to slightly revise the regulatory text for S7.2.1(e) in Labeling to indicate that the markings on the air brake hose directly relate to its type as specified in Table III. As metric air brake hose is not included in Table III, the agency is specifying that it continue to be designated with the letter ``A.''
NHTSA proposed in the brake hose labeling requirements in S7.2.1(e), a labeling provision for brake hoses manufactured for use with more than one type of end fitting, e.g., AI and AII. Upon further review and in light of the comments from the SAE and Parker/Atofina, NHTSA now believes that no such applications exist, because of the large differences in outside diameters between, for example, Type AI and Type AII brake hose. For these reasons, the multiple labeling provisions proposed in the NPRM are removed in the final rule. 2. High Temperature Resistance
NPRMThe high temperature resistance test for air brake hose ensures that there are no cracks or disintegration due to proximity to high temperatures of vehicle components such as engines and transmissions. NHTSA proposed that FMVSS No. 106 adopt the smaller radii test cylinders from SAE J1402 and, for \1/8\ inch and 3 mm, 4 mm, and 5 mm hose, NHTSA proposed that the test cylinder radius of 1 inch as specified in SAE J1402 for \3/16\ inch hose also be used for these hose sizes. As currently indicated in Table IV of FMVSS No. 106, the larger metric sizes of hose (6 mm and above) numerically correspond closely to inch sizes of hose, for example, 6 mm (0.236 inch) is very close to \1/4\ inch (0.250 inch). Accordingly, NHTSA proposed to apply the test cylinder values from SAE J1402 to metric sizes of hose as currently specified in Table IV of FMVSS No. 106. As to SAE J1402's exclusion of fabriccovered air brake hose from the external inspection requirement, NHTSA disagreed that external inspection of such hose is impractical and, therefore, did not propose to incorporate SAE J1402's exclusion.
Public Comments and NHTSA's ResponseThe SAE and Parker/Atofina provided similar comments regarding the proposed test cylinder radii that NHTSA raised in the NPRM. The test cylinder radii were proposed to be decreased from the current values in FMVSS No. 106, Table IV, to smaller values from SAE J1402, Table 4Radius for High Temperature Resistance Test (small radius). For example, the test cylinder radius for a \3/8\inch air brake hose in existing FMVSS No. 106 is 3\1/2\ inches while the test cylinder radius in SAE J1401 for the high temperature resistance test is 1\3/4\ inches, or onehalf the size.
The SAE and Parker/Atofina stated that SAE J1402 is going to be
revised to remove the small radius test cylinders from the high
temperature resistance test. However, in this final rule, the agency is
making FMVSS No. 106 consistent with the current version of SAE J1402, but will be willing to
[[Page 76304]]
consider future alignments between the two standards in future rulemaking.
The agency also notes that in the NPRM, the incorrect value of 3 inches for the large test cylinder was specified for \3/8\ inch hose. NHTSA has corrected the value to 3\1/2\ inches in this final rule.
NHTSA notes that in the NPRM, incorrect test cylinders were included in the proposed Table IV for the adhesion test of wire reinforced hose. The agency stated that the values from SAE J1402, Table 4, should be used (small radius), while in fact SAE J1402 references the radii in Table 1 for this test (large radius). In the final rule, NHTSA retains the correct test cylinder values without change.
Comments from the SAE and Parker/Atofina note that the \1/8\ inch size of air brake hose is not produced, therefore, the test cylinder specification for that size hose is not needed in Table IV of FMVSS No. 106. The agency agrees and in the final rule, removes references to \1/ 8\ inch size of air brake hose from Table IV.
As currently stated in FMVSS No. 106, the required performance of a brake hose after being subjected to the test requirements in the high temperature test is that the brake hose shall not show external or internal cracks, charring, or disintegration visible without magnification. Under the high temperature resistance requirements in SAE J1402, the external surface of fabriccovered hoses is excluded from this inspection, stating that visual inspection is not practical. The agency proposed in the NPRM to keep the requirements in FMVSS No. 106 for external inspection and not include the SAE J1402 exclusion. Both the SAE and Parker/Atofina commented that the SAE J1402 exclusion be kept in place. SAE commented that for hoses covered with a textile braid (fabriccovered), this braid does not show cracks from exposure to ozone nor does it crack due to the high temperature test.
NHTSA does not understand the need to exclude external inspection of the hose if, as Parker/Atofina and the SAE comments indicate, those hoses with textile braid covering will not crack. The inspection is visual, and does not require special equipment or magnification, nor does it require removal of the fabric covering to inspect the hose beneath it. By having such an exclusion, conceivably, a fabriccovered brake hose that did show external cracks would be considered to have passed the test. NHTSA does not believe there is any reason to add the exclusion for external inspection. Further, the agency is specifying only the larger test cylinder sizes for this test, and this should further minimize the likelihood of failure compared to the requirements currently in SAE J1402.
3. Low Temperature Resistance
NPRMNHTSA proposed that the internal surface inspection of air brake hose, as specified in SAE J1402, be incorporated into FMVSS No. 106. However, the agency did not propose to incorporate SAE J1402's exclusion of fabriccovered air brake hose from external inspection.
Public Comments and NHTSA's ResponseThe SAE and Parker/Atofina commented that the \1/8\ inch size of brake hose does not need to be included in Table IV of FMVSS No. 106. NHTSA agrees and has removed the \1/8\ inch size of brake hose from Table IV in the final rule. Both SAE and Parker/Atofina also asked that the external inspection of the hose for cracks excluded fabriccovered hoses, but for the same reasons as described in the discussion on high temperature test requirements, NHTSA does not include this exemption in the final rule.
4. Ozone Resistance
NPRMSince NHTSA proposed that the ozone concentration for hydraulic brake hose be changed from 50 pphm to 100 pphm, NHTSA proposed to specify the higher ozone concentration (100 pphm) for air brake hose as well. The agency tentatively concluded it is appropriate to specify the same concentration of ozone for testing all types of brake hoses.
Public Comments and NHTSA's ResponseSAE, Parker/Atofina, and Goodyear correctly indicated that the proposed ozone concentration should be specified as 100 parts per hundred million, not by parts per million. The correct concentration (100 parts per hundred million) is specified in this final rule.
NHTSA notes that in the NPRM, the ozone test for air brake hose was incorrectly identified as S8.14. A new section of FMVSS No. 106 for the ozone resistance test is not needed since the ozone test is already included in S8.4. In this final rule, the ozone test is correctly identified as S8.4. Thus, the constriction requirements that were proposed to be in S8.15 are now in S8.14.
5. Adhesion
NPRMNHTSA proposed to incorporate the SAE J1402 adhesion test for wirereinforced air brake hose into FMVSS No. 106, with the exception of the steel ball sizes as discussed below. Also, to incorporate SAE J1402's specifications into FMVSS No. 106, NHTSA proposed that rather than specifying steel ball diameters for each hose size, the steel ball should be specified as having a diameter that is 75 percent of the nominal inside diameter of the hose. This would allow for testing of any and all sizes of hose.
The agency also proposed to specify use of a plug gauge rather than a steel ball for constriction testing of other types of hose to which FMVSS No. 106 applies. For the adhesion test, however, it would not be possible to use a plug gauge because the hose is closed off at both ends during the test. Accordingly, NHTSA proposed to specify the use of a steel ball to test air brake hose for adhesion. Finally, the agency proposed to update the ASTM tension testing machine reference in S8.9 from the 1964 version currently in FMVSS No. 106 to the latest revision of that standard, Standard Practices for Force Verification of Testing Machines, Designation E499.
Public Comments and NHTSA's ResponseThe SAE and Parker/Atofina commented that they prefer the 73 percent of nominal inside diameter specification, which would allow the use of standard size test balls. Also, the size difference between a 73 and 75 percent ball size is small (0.008 inches for a \13/32\inch brake hose). NHTSA agrees that the difference is not significant and adopts the 73 percent requirement in the final rule.
NHTSA also notes that the incorrect test cylinder radii were proposed for the adhesion test of wirereinforced air brake hose. The small test cylinders from SAE J1402 Table 4 were proposed in the NPRM, but the correct radii from SAE J1402 Table 1 are included in this final rule.
6. Air Pressure (Leakage)
NPRMThe SAE J1402 specifications for hose leakage are more severe than those presently in FMVSS No. 106. NHTSA proposed incorporating the flexure/pressure test from SAE J1402 into FMVSS No. 106, with some modifications. NHTSA noted that the test procedure in SAE J1402 includes tolerances on the pressure requirements for determining whether the hose leakage rate is acceptable upon completion of the flexure test. The agency described how, if these tolerances were applied in various manners, it may not be possible to determine the pass/fail performance of a brake hose during a test.
Therefore, in the NPRM, we proposed an alternative, to modify the
requirements to ensure there would be a pass or fail criterion. NHTSA also proposed to modify SAE J1402's test
[[Page 76305]]
procedures by specifying the thickness of the orifice during the final
leak check. The thickness of the orifice, and not only the diameter of
the orifice, affects the rate at which air can be supplied to the hose.
The rate at which air is supplied to the hose would be critical if a
small amount of hose leakage is present during the final leakage test.
NHTSA proposed specifying an orifice thickness of 0.032 inches (\1/32\
inch), which is the same thickness specified for the orifice in FMVSS
No. 121 at S5.3.5, Control signal pressure differential for converter
dollies and trailers designed to tow another vehicle equipped with air
brakes. NHTSA tentatively concluded that this proposed orifice
dimension would supply air at a greater rate than any thicker orifice
while still providing sufficient mechanical strength to withstand the test conditions.
The agency proposed to adopt the lowest test pressure (140 psi) in the brake hose during the leakage test from the range provided in SAE J1402 (140 to 160 psi). The applied supply pressure to a restrictive orifice was proposed to be at the midpoint of the pressure range, 150 psi. Thus, the supply pressure exceeds the required pressure that is to be maintained in the brake hose, allowing a small amount of leakage to be present, but not permitting excessive leakage to be present.
Public Comments and NHTSA's ResponsesThe SAE and Parker/Atofina both stated that the agency is proposing to change the SAE test, creating a new requirement. The commenters stated that it does not reflect good test methodology to require 150 psi supply pressure with no tolerance, or 140 psi with no tolerance in the brake hose within the two minute period. However, neither commenter recommended an alternative to NHTSA's proposal, other than to adopt the exact procedure in SAE J1402. Both commenters stated that the agency's proposal to adopt a thickness requirement for the orifice has some technical value.
While the agency has considered the comments, the commenters did not provide recommendations as to test pressures that the agency could adopt in the final rule. The agency believes that by specifying the minimum required pressure of 140 psi in the brake hose, while supplying air at the midpoint pressure of 150 psi through an orifice of minimal thickness that is least restrictive to air flow, a reasonable balance in test conditions is achieved. Therefore, NHTSA is making final the air pressure (leakage) test that it proposed in the NPRM.
NHTSA believes that measuring the leakage using a mass flow meter, as is done for test leaks of plastic air brake tubing, may be preferable to the method in this final rule. NHTSA may consider raising this issue in a future rulemaking.
7. Tensile Strength
NPRMAs currently in effect, FMVSS No. 106 includes different tensile strength requirements for air brake hoses if those hoses are used: (a) Between the vehicle frame and axle, or between a towing and towed unit; or (b) in any other application. The tensile strength requirements for brake hose assemblies in the former case are significantly higher than those requirements in the latter case. Because the agency proposed separate requirements for plastic tubing in a new section of FMVSS No. 106, NHTSA proposed to delete the lower tensile strength limits for hoses that are used for purposes other than connections between a frame and axle or between a towed and towing unit, and require the higher tensile strength requirements for all brake hoses. SAE J1402 only includes the higher tensile strength requirements.
The agency proposed that all rubber brake hoses meet the requirements for a hose that is used between a frame and an axle or between a towed and a towing unit. NHTSA tentatively concluded that rubber hoses are no longer used extensively for other purposes on heavy vehicles, as plastic tubing is used for most chassis plumbing of air systems. NHTSA tentatively concluded that these rubber hoses are of sufficient diameter to have the mechanical strength to meet the higher, frametoaxle tensile strength requirements. NHTSA also solicited comments on any alternate tensile strength requirements that might be appropriate for rubber hoses.
Public Comments and NHTSA's ResponseThe SAE recommended that the SAE J1402 tensile strength testing be adopted. SAE did not elaborate on its recommendation. Parker/Atofina recommended keeping the current FMVSS No. 106 requirements with the high and low tensile strength requirements depending on application of the hose assembly. Parker/ Atofina stated that the lower tensile strength requirements are still used in applications other than connections between a towed and a towing unit, and to raise these requirements to the higher tensile strength would add significantly to hose cost. No cost data was provided for the agency to evaluate.
In evaluating the tensile strength test requirements, NHTSA notes that it proposed different tensile strength requirements for plastic air brake tubing depending on the application of the product (e.g., between towing and towed unit, or in chassis plumbing applications), based on the current tensile strength requirements for air brake hoses in S7.3.10 of FMVSS No. 106. The reason for the different strength requirements is to accommodate different styles of end fittings. Thus, the end fittings for a brake hose or plastic tubing used between a towing and towed vehicle provide the highest tensile strength possible to prevent separation of the end fittings. In other applications, such as chassis plumbing, lower tensile strength requirements apply that permit the use of fittings designed for ease of assembly on chassis plumbing (such as pushtoconnect fittings used with plastic tubing).
NHTSA did not believe that air brake hose is for chassis plumbing (having been replaced by plastic tubing) and therefore proposed to delete the lower tensile strength requirements for this type of brake hose. Parker/Atofina however, states that this is not the case, and the agency believes that Parker/Atofina is referring to the higher cost of highstrength end fittings and/or the longer assembly time required for these fittings. Therefore, in this final rule, the agency is not deleting the lower tensile strength requirements for end fitting retention for air brake hose, to avoid changes to vehicle manufacturing in situations where this type of air brake hose is used for chassis plumbing. The end fitting tensile strength requirements will therefore be similar for air brake hose and plastic air brake tubing. 8. Minimum Bend Radius
NPRMNHTSA tentatively concluded it would not be appropriate to add SAE J1402 requirements for minimum bend radius to FMVSS No. 106 because FMVSS No. 106 regulates the properties of brake hoses as stand alone motor vehicle equipment rather than use requirements. NHTSA did not propose to include a reference to the minimum bend radii from Table 1 in SAE J1402 as the minimum installation bend radii for brake hose as installed on vehicles.
Public Comments and NHTSA's ResponseBoth the SAE and Parker/
Atofina asked that the minimum bend radii from Table 1 in SAE J1402 as
the minimum installation bend radii for brake hose installed on
vehicles be included to benefit users (installers) of the brake hose.
The agency notes that in Section 3.3.1 of J1402, smaller installation radii may be appropriate for
[[Page 76306]]
some brake hoses. Therefore, in the final rule, NHTSA is not specifying
installation bend radii. NHTSA believes individual brake hose
manufacturers are in the best position to determine minimum bend radii for hose to be installed in motor vehicles.
D. Vacuum Brake Hoses
1. Swell (Fuel Resistance)
NPRMNHTSA proposed that Reference Fuel B as specified in SAE J1403 be used for the swell test in FMVSS No. 106. NHTSA also proposed that the plug gauge method (in lieu of the steel dropball method) be kept in place in TP106 for swell testing of vacuum brake hoses.
NHTSA proposed that the specifications of FMVSS No. 106 and SAE J1403 be combined as follows. Following the fuel conditioning using Reference Fuel B and the constriction test, each vacuum hose would be subjected to a vacuum of 26 inches of Hg for ten minutes, with no visible collapse or leakage of the hose permitted (as currently specified by FMVSS No. 106). Then, for hoses constructed of two layers or more, a layer adhesion test would be conducted with a specified performance of 8 poundsperinch minimum separation force (as specified by SAE J1403). NHTSA proposed that this adhesion test only be applied to multilayer hoses for two reasons. First, the agency tentatively concluded that single layer hose cannot be tested easily. Second, NHTSA tentatively concluded that single layer hose that have lost mechanical integrity would not be able to pass the visual collapse or no leakage specification during the vacuum test and, as such, failure would already be detected prior to completion of the vacuum test.
NHTSA also proposed to update the ASTM test procedure referenced in S10.7 for the swell test to the current revision, D47198e1.
Public Comments and NHTSA's ResponseGoodyear supported the current SAE J1403 test sequence consisting of fuel soak, restriction (constriction) ball test, vacuum collapse test, and layer adhesion test with a minimum separation strength of 6 pounds per inch. Goodyear commented that the agency's proposed plug gauge for constriction testing, shown as Figure 4, has only three inches of length and would not be able to pass through a test sample of vacuum hose that is 12 inches in length. Further, the vacuum brake hose may have some curvature that would not permit a straight gauge to pass through it. For these reasons, Goodyear recommended that a rolling ball be used to verify the internal dimensions of vacuum brake hose during the swell test.
In responding, the agency begins by noting that preformed vacuum brake hoses would have significant curvature molded into them, and standard vacuum brake hose may also have some natural curvature as described by Goodyear. NHTSA also notes that in the existing and proposed FMVSS No. 106 regulatory text, the method of verifying the inside diameter of the vacuum brake hose is not provided. As noted in the NPRM, the method is identified as a plug gauge in the agency's current test procedure, TP106. For the final rule, the agency has decided to provide the option of using a drop ball for both constriction tests and verification of the inside diameter during the swell test, and to also permit the use of a standard plug gauge or an extended length plug gauge. The fact that several options are provided to brake hose manufacturers is consistent with constriction testing for other types of brake hoses in FMVSS No. 106, where more than one method may be employed (by NHTSA and brake hose manufacturers) due to the variety of end fitting designs that may preclude the use of the plug gauge. In this final rule, NHTSA is incorporating into FMVSS No. 106 the three constriction test methods to be used in the swell test.
In the NPRM, NHTSA proposed an adhesion strength test requirement
of 8 pounds per inch. Goodyear stated that the value should be 6 pounds
per inch, as stated in SAE J1403. The correct value of 6 pounds per inch adhesion strength requirement is in this final rule.
E. Plastic Air Brake Tubing
1. General Comments
In the NPRM, NHTSA stated that plastic air brake tubing is generally manufactured from nylon but the generic term, ``plastic'' is used to account for other types of plastic that may be used for air brake tubing. The comments on the proposal for requirements for plastic air brake tubing, plastic air brake tubing assemblies, and plastic air brake tubing end fittings fell into two groups: (a) Manufacturers currently manufacturing air brake tubing from polyamide (nylon) requesting that this material specification be included in FMVSS No. 106; and (b) manufacturers that may be considering manufacturing air brake tubing from materials other than nylon, that did not support including this material specification (plastic) in FMVSS No. 106.
Parker/Atofina stated that by not including additional material property tests into FMVSS No. 106, there would be insufficient safeguards for the performance of alternate tubing made from unproven and unspecified polymers that would create a significant product design risk. It also stated that the material specification of generic nylon is not design restrictive, but offers thermoplastic tubing manufacturers great latitude in product design options.
SMC stated that not including the material specification in FMVSS No. 106 leads to an issue that is being addressed in the SAE committee that is responsible for SAE J2547, Alternate Nonmetallic Air Brake System Tubing. Namely, the test should be application specific and not a material validation test like the burst pressure test in SAE J844. Different tube material may affect the retention of the tubing in the fitting per the SAE J1131 requirements. Until further evaluation is conducted on the new tubing materials with all fitting supplied in the industry, leaving the material open to the tubing manufacturers' discretion may lead to problems with the tube connection.
HPP stated that SAE J844 takes into account that the materials are polyamides. To exclude this requirement, additional tests would need to be introduced to ensure that longterm properties of tubing made from other materials meet the inuse requirements. HPP cited, for example, that there is no requirement for a hightemperature burst test at elevated pressures, while polyamides are known to possess the longterm properties for this requirement.
DuPont stated that the agency correctly points out in the NPRM that a material and construction specification is design restrictive. It notes that while polyamides used under SAE J844 have performed with an admirable safety record, it has a negative impact on innovation and commerce. DuPont also encouraged the elimination of any reference to specific types of construction, specifically regarding Type A (unreinforced) and Type B (reinforced) tubing. DuPont stated that any style of construction that passes the rigorous test procedures and dimensional requirements set forth in the proposal should be permissible.
In this final rule, NHTSA has decided to keep the generic
terminology of plastic air brake tubing, rather than adopt the
specification for nylon (polyamide) material. Regarding concerns that
materials other than nylon might be inferior when used in air brake
tubing, NHTSA notes that it proposed 24 performance test requirements [[Page 76307]]
(proposed S11.3.1 through proposed S11.3.24), and is adopting twenty
two of those requirements in the final rule. NHTSA believes that these
extensive requirements will ensure that alternative air brake tubing
materials are subjected to rigorous testing to provide safe service in air brake systems.
HPP stated that if the requirements in SAE J844 are performed on air brake tubing made from materials other than nylon, additional tests might be appropriate, such as a hightemperature burst test. However, HPP did not provide any test parameters that the agency could evaluate. NHTSA notes in the section below that hightemperature conditioning requirements for plastic air brake tubing have been included for adoption in FMVSS No. 106.
With regard to the agency's statements in the NPRM that air brake tubing must be either Type A, single layer, unreinforced construction, or Type B, two layer, reinforced construction, the agency has reviewed the comments on this subject and has decided not to adopt these requirements in the final rule. Additional details that formed the agency's decision on this subject are included in the sections below. 2. Construction
NPRMThe NPRM solicited comments on whether air brake tubing should be designated as Type Aa nonreinforced, singlelayer tubing (designated for small diameter tubing in SAE J844), or as Type B constructed from two layers of material with a reinforcing braid at th
FOR FURTHER INFORMATION CONTACT
For nonlegal issues, Mr. Jeff Woods, Vehicle Dynamics Division, Office of Vehicle Safety Standards (Telephone: (202) 3666206) (Fax: (202) 3664921).
For legal issues, Ms. Dorothy Nakama, Office of the Chief Counsel (Telephone: (202) 3662992) (Fax: (202) 3663820).
You may send mail to both of these officials at: National Highway Traffic Safety Administration, 400 Seventh St., SW., Washington, DC 20590.